Manufacture of objects from cellulose acetate.



UNITED STATES PATENT OFFICE.

ALBERT SCHLOSS, OF STETTIN, GERMANY, AS SIGNOR TO FURST GUIDO DONNERS MAROKSOHE KUNSTSEIDEN & ACETATWERKE, OF SYDOWSANE, NEAR STETTIN, I

GERMANY.

MANUFACTURE OF OBJECTS FROM CELLULOSE ACETATE.

Specification of Letters Patent. Application filed March 12, 1909. Serial No. 482,950.

Patented May 18, 1909.

To all whom it may concern:

Be it known that I, ALBERT SoHLoss, a subject of the King of Prussia, residing in Stettin, Prussia, Germany, have invented certain new and useful Improvements in the Manufacture of Objects from Cellulose Acetate.

reasons, of which perhaps the most important is the fact that the solutions are very sensitive to the'presenceof watera very small proportion of the latter being sufficient to render the solutions useless by partially precipitating the cellulose-acetate.

have discovered in formic acid a solvent for cellulose acetate which overcomes all the objections mentioned and provides a commercially successful process. As a solvent formic acid at least equals the expensive solvents abovementioned and is much superior to glacial acetic acid. Furthermore the formic acid solution is not at all sensitive to the presence of water and can stand a large percentage without being unfavorably affected. Furthermore. formic acid is very volatile and 1s readily decomposed, so that it may be used in practically all the industrial processes in which a cellulose-acetate solution may be employed, for instance, for producing coatings, impregnations and all sorts of solids, especially textile fibers.

' 'An unexpected and marked advantage'in the use of formic acid as a solvent has been discovered, namely that a thread (i the spmning process, for example) of su cient strength is at once. produced when thelsolution 15 squirted into an aqueous, recipitating bath of suitable character. T tion in the resent case is believed to be due to the fact t at the skin formed upon the surface of the The solvents now generally used in the e rapid acfilament as-soon as it enters the preclpltating bath is readily penetrated by.

orxmc acid and water, so that thecoagulation process rapidly extends into the interior of the thread thus imparting the necessary strength almost at once. Filaments so spun may be subsequently twisted, reeled and submitted to any appropriate treatment.

In point of economy the present formic acid process is the e ual of any of the others, since the formic acid used may be recovered readily as acetic acid. Furthermore, the initial cost is slight, inasmuch as formic acid is low ricedand indeed by recently developed processes, it may be obtained at even less expense than acetic acid.

A suitable solution may be readily made in accordance with the present invention by adding dry cellulose acetate to formic acid and stirrin until the acetate-is dissolved. But the soIution may be produced equally wellby substituting formic acidfor acetic acid, for instance, as a diluent or solvent in any of the known processes for the acetylization of cellulose (hydro,-, oxy-, cellulose etc), by means of acetic anhydrid in the presence of sulfuric acid or other stimulant.

Thus a formic acid solution containing a v certain quantity of acetic acid, is directly obtained in the acetylizing process. It follows-from this that one or more other diluting agents, may be mixed with the formic acid as, circumstances or desired effect may require. Similarly any other appropriate ingredients may of course be used for softening the products to be made of the solution or for any other purpose Whatever.

I claim as my invention:

. 1. In the manufacture of objects from cellulose acetate, the subjection of the cellulose acetate to the action of formic acid as a solvent, substantially as described.

2. In the manufacture of objects from cellulose acetate, the subjection of the cellulose acetate to the action of formic acid as a solvent and the introduction of the solution so formed into an aqueous recipitating bath, substantially as describetil In testimony whereof I have signed my name to this specification, two subscribing Witnesses.

ALBERT SCHLOSS.

- Witnesses:

P. ERSBAOH, W. MANSHE.

in the presence of 1 00 

